Okay, tumors are scary already, right? Lumps of whatever the hell inside of your body killing you slowly.
Teratomas are about the scariest version of tumors possible.
They usually form with teeth, eyes and even a loving face. Search up an image of them if you're ready for some loving disgusting stuff. Seriously, a teethed tumor.
My brother's comment: "Good lord that's loving disgusting. I think I lost my appetite"